I dispute this. If your confident the coin your buying is close to its base value the risk is not that great(providing the coin isnt cracked or delisted). have gone all in on a few coins so far and have not regretted any of them. The funny thing is that I argued your position against an experienced trader when I was less experienced, so i get your perspective.
The coins I went all in on before lbc were STR@ 400 sats (sold at 2400) zcash @ .05 (sold at .13) and SC @ 110 satoshi (sold at 530). This all in trades have given me most of profits in the last few months.
Actually I agree with you. Going all in on 1-3 coins is good if you don't pick them randomly. I also made fortunes with buying really huge chunks of projects I thought will have a bright future. As long as you don't get nervous from the waves, going all in and holding some months can net you neat profits. It's just a matter of how wise youre chosing the projects you're investing into. If you invest into shit, you get burned. If you invest in good stuff like LBRY, chances are you will get nice profits.